The present invention relates to a system for treating vascular disease. More specifically, the present invention relates to a system for treating a lesion at a bifurcation in the vasculature.
Vascular disease currently represents a prevalent medical condition. Typical vascular disease involves the development of a stenosis in the vasculature. The particular vessel containing the stenosis can be completely blocked (or occluded) or it can simply be narrowed (or restricted). In either case, restriction of the vessel caused by the stenotic lesion results in many well known problems caused by the reduction or cessation of blood circulation through the restricted vessel.
A bifurcation is an area of the vasculature where a first (or parent) vessel is bifurcated into two or more branch vessels. It is not uncommon for stenotic lesions to form in such bifurcations. The stenotic lesions can affect only one of the vessels (i.e., either of the branch vessels or the parent vessel), two of the vessels, or all branch vessels.
A number of different procedures have been developed to treat a stenotic lesion (stenosis) in the vasculature. The first is to deform the stenosis to reduce the restriction within the lumen of the blood vessel. This type of deformation (or dilatation) is typically performed using balloon angioplasty.
However, when the lesion is formed in a bifurcation, conventional balloon angioplasty can be somewhat cumbersome. In some cases, two separate guidewires are used. However, where only one guidewire is used, the guidewire is first introduced into one of the branch vessels of the bifurcation. The dilatation balloon is then advanced over the guidewire so the distal end of the dilatation balloon is in the branch vessel. The balloon is then inflated a number of times, in a known manner, to accomplish dilatation.
The balloon is then withdrawn proximal of the bifurcation. The guidewire is then withdrawn and manipulated into the other branch vessel of the bifurcation. The balloon is then advanced over the guidewire, again, and inflated to dilate the second branch vessel.
Not only is this process somewhat cumbersome, other problems result as well. For example, when the angle between the branch vessels in the bifurcation is fairly small, inflation of the dilatation balloon in one branch vessel can cause the ostium of the other branch vessel to collapse. This results in ineffective dilatation by restricting flow to the other branch vessel.
Further, locating both branch vessels can be quite difficult. For example, once the first branch vessel is located under conventional visualization techniques (such as with the use of contrast medium), that vessel is dilated. After withdrawing both the guidewire and the dilatation catheter proximal of the bifurcation, the physician must then attempt to locate the second branch vessel. This can require the introduction of other devices into the vasculature and the region of the bifurcation. This can be somewhat cumbersome.
Vascular stents are also currently well known, and are deployed as another technique for treating vascular lesions. Vascular stents typically involve a tubular stent which is movable from a collapsed, low profile, delivery position to an expanded, deployed position. The stent is typically delivered using a stent delivery device, such as a stent delivery catheter. In one common technique, the stent is crimped down to its delivery position over an expandable element, such as a stent deployment balloon. The stent is then advanced (using the catheter attached to the stent deployment balloon) to the lesion site under any suitable, commonly known visualization technique. The balloon is then expanded to drive the stent from its delivery position to its deployed position in which the outer periphery of the stent frictionally engages the inner periphery of the lumen. In some instances, the lumen is predilated using a conventional dilatation catheter, and then the stent is deployed to maintain the vessel in an unoccluded, and unrestricted position.
While there have recently been considerable advances in stent design and stent deployment techniques, there is currently no adequate method of treating bifurcation lesions, particularly where both downstream branch vessels are affected by the lesion. Current techniques of dealing with such lesions typically require the deployment of a slotted tube stent across the bifurcation. However, this compromises the ostium of the unstented branch.
Further, once the first stent is deployed, the treating physician may then advance a dilatation balloon between the struts of the stent already deployed in order to dilate the second branch vessel. The physician must then attempt to maneuver a second stent through the struts of the stent already deployed, into the second branch vessel for deployment. This presents significant difficulties. For example, dilating between the struts of the stent already deployed tends to distort that stent. Further, deploying the second stent through the struts of the first stent is not only difficult, but it can also distort the first stent.